Clinical presentation: A 44-year-old woman was referred for follow-up of hypothyroidism which has been treated for 18 years.

Palpation. No abnormality.

Laboratory tests: TSH 0.33 mIU/L, FT4 15.4 pM/L on daily 112.5 microgram levothyroxine. The aTPO level was above 1300 U/mL at the beginning of replacement therapy.

Ultrasonography. The thyroid was atrophic and composed of moderately and deeply hypoechogenic parts. There were no nodules in pathological sense.

Suggestion: to decrease the dose of levothyroxine to daily 100 microgram.